The lipid-containing, double-stranded RNA bacteriophage 06, for Pseudomonas phaseolicola is being extensively characterized both chemically and biologically. Parameters affecting dsRNA synthesis in infected cells are being studied. A carrier state of 06 has been discovered in our laboratory. The stability and nature of the relationship with the host will be determined by looking for dsRNA, ssRNA, dsDNA, or ssDNA which hybridizes with 06 RNA. Temperature-dependent cross-over of Pseudomonas phaseolicola phages to Xanthomonas species will be studied in more detail.